An inhaler is an apparatus used for disinfection, treatment and the like of bronchi and is in widespread use in medical institutions and at home as treatment equipment for treating respiratory disease such as bronchitis or asthma. In particular, an inhaler ejecting atomized chemical solution for the treatment purpose is called inhalation treatment equipment.
Inhalers may mainly be classified, according to the atomization principles, into three categories: compressor-type inhalers, ultrasonic-type inhalers, and ultrasonic-mesh-type inhalers. A compressor-type inhaler is an inhaler which generates spray particles by mixing liquid to be atomized into compressed air delivered from a compressor and then causing the compressed air including the liquid to impinge on a wall called a baffle to scatter the liquid. A ultrasonic-type inhaler is an inhaler which forms liquid into spray particles by driving an ultrasonic element to apply high-frequency vibration to liquid and using cavitation generated by this high-frequency vibration. A ultrasonic-mesh-type inhaler is an inhaler which forms spray particles by supplying liquid between a vibration element and a mesh member arranged to oppose each other and driving the vibration element in this state to provide vibration to the liquid, allowing the liquid to pass through holes provided in the mesh, thereby pulverizing the liquid.
An inhaler generally includes an apparatus body including an aerosol generation portion and an aerosol lead-out portion. The aerosol generation portion is a part that generates aerosol by atomizing liquid into spray particles and applying this spray particles to the introduced outside air. On the other hand, the aerosol lead-out portion is a part that ejects the generated aerosol to the oral cavity or nasal cavity of a user, and employs a mouthpiece, a nosepiece, a mask or the like.
The aerosol generation portion is provided with a pressure regulation opening for regulating the internal pressure inside of aerosol (an auxiliary outside air introduction opening for introducing the outside air into the apparatus body in an auxiliary manner when a user performs an exhalation operation), and the aerosol lead-out portion is provided with an aerosol lead-out opening for leading the generated aerosol out. In addition, the aerosol lead-out portion is provided with an exhalation discharge opening for discharging the breath exhaled by the user to the outside. Usually, among these openings provided for the apparatus body, the pressure regulation opening and the exhalation discharge opening have respective check valves attached thereto to close the respective openings. Each of these check valves is provided to allow the user to breathe smoothly without suffocation and also to inhale aerosol efficiently. The check valve provided for the pressure regulation opening is generally called an inhalation valve, and the check valve provided for the exhalation discharge opening is generally called an exhalation valve.
There are mainly two usage manners as manners of using an inhaler with a mouthpiece. In one of the usage manners, a user puts a mouthpiece into the mouth, and this usage manner is intended for users having relatively large vital capacity of the lung. In this usage manner, the check valve function of the aforementioned inhalation valve and exhalation valve advantageously allows the user to inhale the generated aerosol with almost no loss. In the other usage manner, a user confronts a mouthpiece to take in aerosol ejected from the mouthpiece without putting the mouthpiece into the mouth, and this usage manner is intended for users having relatively small vital capacity of the lung. Although this usage manner disadvantageously causes much loss of the generated aerosol as compared with the aforementioned usage manner of putting the mouthpiece into the mouth, it is an effective manner in that even infants or elderly people having small vital capacity of the lung can use inhalers relatively easily. Here, even in this usage manner of not putting the mouthpiece into the mouth, the generated aerosol can be ejected from the aerosol lead-out opening with almost no loss, because of the check valve function of an inhalation valve and an exhalation valve. However, since the user does not put the mouthpiece into the mouth, all of the ejected aerosol is not taken in by the user, and in this respect, the loss of aerosol is increased.
In designing inhalers, it is important to consider that aerosol can be inhaled efficiently by users, whichever of these usage manners is employed. Nevertheless, from a hygiene stand point, inhalers require cleaning and disinfection operations after use by disassembling the apparatus body, so that it is also important to simplify the apparatus configuration as much as possible to facilitate disassembly and assembly operations. If the apparatus configuration can be simplified, provision of inhalers at low costs become possible, accordingly.
In particular, unlike the other components, the inhalation valve and the exhalation valve are formed of flexible members, are thus difficult to handle, and in addition, are likely to be broken or lost during disassembly and assembly operations, and therefore their elimination is favorable. However, with the mere elimination of the inhalation valve and/or the exhalation valve, much precious aerosol leaks out from the pressure regulation opening and the exhalation discharge opening, thereby significantly reducing the inhalation efficiency.
Then, an inhaler and an inhaler mouthpiece are known as disclosed in Japanese Utility-Model Laying-Open No. 4-95046 (Patent Document 1) and Japanese Patent Laying-Open No. 5-337183 (Patent Document 2), in which the apparatus configuration is simplified by eliminating an exhalation valve, while loss of aerosol (here, mainly, leakage of aerosol from an exhalation discharge opening during inhalation) which may be caused by eliminating an exhalation valve is reduced as much as possible.
FIG. 21 is a longitudinal cross-sectional view of an inhaler mouthpiece disclosed in the above-noted Patent Document 1, and FIG. 22 is a front view as viewed from arrow XXII shown in FIG. 21. As shown in FIG. 21 and FIG. 22, an inhaler mouthpiece 250 disclosed in the above-noted Patent Document 1 includes an inhalation portion 252 having openings at opposite ends and an introduction portion 251 having an opening at one end and communicating with an aerosol generation portion at the other end, and is structured such that introduction portion 251 is inserted into inhalation portion 252 from the opening in such a manner that a part of the opening at one end of inhalation portion 252 is open to the outside.
This structure will be described in more detail. A lead-out flow passage 204 extending from the aerosol generation portion to aerosol lead-out opening 205 is constituted with a flow passage portions 204A, 204C provided in introduction portion 251 and a lower part of a flow passage portion 204B provided in inhalation portion 252, and a discharge flow passage extending from aerosol lead-out opening 205 to exhalation discharge opening 206 is constituted with an upper part of flow passage portion 204B provided in inhalation portion 252 and a flow passage portion 204E also provided in inhalation portion 252. Then, a narrow portion 254 is provided at a part of introduction portion 251 such that the cross section of flow passage portion 204C is smaller than the cross section of flow passage portion 204A. In addition, an aerosol outflow opening 255 which is a portion where aerosol flows out from introduction portion 251 to inhalation portion 252 is provided in inhalation portion 252, and an exhalation discharge opening 206 is provided at an end portion of flow passage portion 204E that is a portion positioned in a rear direction from this aerosol outflow opening 255.
Because of such a configuration, as shown in FIG. 21, at the time of inhalation, aerosol passes through the lower side of flow passage portion 204B provided in inhalation portion 251 to reach aerosol lead-out opening 205, and at the time of exhalation discharge, exhalation passes through the upper side of flow passage portion 204B provided in inhalation portion 251 to reach exhalation discharge opening 206, so that prevention of loss of aerosol and elimination of an exhalation valve are realized at the same time.
FIG. 23 is a longitudinal cross-sectional view of an inhaler mouthpiece disclosed in the above-noted Patent Document 2. As shown in FIG. 23, an inhaler mouthpiece 350 disclosed in the above-noted Patent Document 2 includes a lead-out flow passage 304 serving as an ejection flow passage for spray particles which is separated by a partition wall 354 provided inside thereof, and a discharge flow passage serving as a release flow passage for backflow. Lead-out flow passage 304 is formed to extend from an opening at one end that communicates with an aerosol generation portion to aerosol lead-out opening 305 which is an opening at the other end, and the discharge flow passage is formed to extend from aerosol lead-out opening 305 to exhalation discharge opening 306.
This structure will be described in more detail. Lead-out flow passage 304 extending from the aerosol generation portion to aerosol lead-out opening 305 is configured with a first flow passage portion 304A provided in a lower-side tubular portion 351 extending upward from the aerosol generation portion, a lower part of a second flow passage portion 304B provided in an upper-side tubular portion 352 extending obliquely forward to reach aerosol lead-out opening 305, and a corner flow passage portion 304C connecting these first flow passage portion 304A and second flow passage portion 304B with each other, and the discharge flow passage extending from aerosol lead-out opening 305 to exhalation discharge opening 306 is constituted with an upper part of second flow passage portion 304B provided in upper-side tubular portion 352 and a flow passage portion 304E also provided in upper-side tubular portion 352. Then, a narrow portion is formed by partition wall 354 such that the cross section of corner flow passage portion 304C is smaller than the cross section of flow passage portion 304A. In addition, an aerosol outflow opening 355, which is a part where aerosol flows out from this narrow portion to second flow passage portion 304B, is provided in upper-side tubular portion 352, and an exhalation discharge opening 306 is provided in flow passage portion 304E positioned in a rear direction from this aerosol outflow portion 355.
Because of such a configuration, as shown in FIG. 23, at the time of inhalation, aerosol passes through the lower side of second flow passage portion 304B provided in upper-side tubular portion 352 to reach aerosol lead-out opening 305, and at the time of exhalation discharge, exhalation passes through the upper side of second flow passage portion 304B provided in upper-side tubular portion 352 to reach exhalation discharge opening 306, so that prevention of loss of aerosol and elimination of an exhalation valve are realized at the same time.    Patent Document 1: Japanese Utility-Model Laying-Open No. 4-95046    Patent Document 2: Japanese Patent Laying-Open No. 5-337183